[1] UCL, Ctr Ageing Populat Studies, Res Dept Primary Care & Populat Hlth, Rowland Hill St, London NW3 2PF, England
[2] UCL, Ctr Dementia Palliat Care Res, Marie Curie Palliat Care Res Dept, Div Psychiat, Tottenham Court Rd, London W1T 7NF, England
[3] UCL, Res Dept Primary Care & Populat Hlth, Priment Clin Trials Unit, London, England
[4] North Middlesex Univ Hosp, Barnet Enfield & Haringey Mental Hlth Trust Liais, Sterling Way, London, England